This invention pertains to pressure maintenance assemblies, more particularly to pressure regulating valves for a water well system.
Domestic water systems are used to supply running water to households from a local water source, such as a well, lake, reservoir, cistern or other potable water source. A conventional water system includes an electric pump, a pressure tank and a pressure switch. The pressure tank allows the operation of the system within a preset range without undo cycling of the pump. This range is determined by the pressure switch that activates and deactivates the pump. The pump is connected to the inlet port of the water system and is controlled by the pressure switch, which measures fluctuations in water pressure within the pressure tank. Water is initially supplied to a user from the pressure tank. The pressure switch detects the resulting decrease in water pressure to the preset cut-in pressure and turns the pump on, increasing the flow of water to the inlet port of the water system and providing flow to both meet system demand and to re-fill the pressure tank. To prevent the water pressure from damaging the components of the water system, the pressure switch has a cut-out pressure at which it turns the pump off. As the pressure tank is refilled, its pressure increases until the cut-out pressure is achieved and the pump is turned off. However, during periods of peak demand, like multiple fixture or appliance usage and irrigation, the tank pressure increases and decreases quickly, causing the pump to cycle on and off again within a short time. The resultant water pressure fluctuation from high to low and back to high is bothersome to the user, and the rapid pump cycling causes increased wear and tear to the pump and motor.
In one aspect the invention is a domestic water well pressure maintenance assembly. The pressure maintenance assembly includes a pressure maintenance valve having an inlet side and an outlet side, a pressure tank in fluidic communication with the outlet side, a pressure switch, and a calibrated bypass. The pressure switch turns the pump on when a pressure in the outlet side is at a cut-in pressure and off when the pressure is at a cut-out pressure. When the valve is closed, the calibrated bypass provides fluidic communication between the inlet side and the outlet side. The size of the calibrated bypass and the size of the pressure tank are adapted and constructed to permit a flow rate between the inlet side and the outlet side that will fill the pressure tank in a time interval less than twice the time required to pump a volume of water that will dissipate heat generated by the pump when it is turned on.
The pressure maintenance valve may further include a movable member interposed between the inlet side and the outlet side, a diaphragm, an adjustable spring, and a communication port providing fluidic communication between the outlet side and the diaphragm via which pressure is imparted on the diaphragm. A pressure drop between the inlet side and the outlet side is moderated by an amount of displacement of the movable member with respect to a first position, and a tension in the spring enables the diaphragm to displace the movable member with respect to the first position against pressure imparted by fluid in the outlet side. The calibrated bypass may include a hole or groove disposed in either the movable member or a seat for the movable member. A number of pump cycles per day may be less than about 40%, about 50%, or about 60% of a number of pump cycles per day in a water system comprising a pump, a pressure switch, and a pressure tank, in which there is not a pressure maintenance valve interposed between the pump and the pressure tank. The outlet side of the valve may comprise first and second outlets, and the second outlet may be adapted and configured to receive the pressure tank. The pressure maintenance assembly may further comprise an accessory fitting threadably attached to the outlet side and adapted and configured to receive one or more of a pressure switch, a pressure gauge, a release valve, and a drain valve. The calibrated bypass may be adapted and constructed to escort sufficient water from the inlet side to the outlet side to cool the pump when the valve is closed while the pump is on.
In one exemplary embodiment, the pump has a capacity between 5 and 15 GPM, the valve has an inlet with a one inch diameter, the pressure tank has a total capacity approximately between 15 and 30 gallons, and the calibrated bypass has a cross-sectional area of about 0.0075 square inches. In another exemplary embodiment, the pump has a capacity approximately between 15 and 30 GPM, the valve has an inlet with a diameter of about 1.25 inches, the pressure tank has a total capacity approximately between 30 and 50 gallons, and the calibrated bypass has a cross-sectional area of about 0.0095 square inches.
In another aspect, the invention is a method of configuring a water well pressure maintenance assembly. The method comprises selected a desired maximum flow rate through a plumbing system in fluidic communication with the assembly, selecting a pump having sufficient capacity to deliver the maximum flow rate, and selecting a valve for the assembly that has a pre-determined pressure drop at the maximum flow rate. The valve comprises an inlet side to which water is provided by the pump, an outlet side from which water is delivered to a user, and a calibrated bypass that provides fluidic communication between the inlet side and the outlet side when the valve is closed. The time required to fill a pressure tank in fluidic communication with the outlet side is less than twice that required to flow sufficient water over the pump to dissipate heat generated by the pump when it is started. The method may further comprise selecting a cut-in outlet side pressure at which the pump is turned on and a cut-out outlet side pressure at which the pump is turned off.
In another aspect, the invention is a method of optimizing a pressure maintenance assembly comprising a valve having an outlet side and an inlet side in fluidic communication with a pump, a pressure tank in fluidic communication with the outlet side, a pressure switch that turns the pump on and off in response to a pressure in the outlet side, and a calibrated bypass that provides fluidic communication between the inlet side and the outlet side when the valve is closed. The method comprises selecting a size for at least one of the pressure tank, the valve, and the calibrated bypass such that a time interval required for the pump to fill the tank is less than twice as long as required to dissipate heat generated by the pump when it is turned on. The selected size may permit the pump to direct sufficient water through the calibrated bypass to cool the pump when the valve is closed. The method may further comprise providing an outlet for the valve that is adapted and constructed to receive the pressure tanks. In addition, the method may comprise providing an accessory fitting threadably attachable to the outlet side and adapted and configured to receive one or more of a pressure switch, a pressure gauge, a release valve, and a drain valve.
In another aspect, the invention is a pressure maintenance valve. The valve includes an inlet side and an outlet side in fluidic communication, a movable member interposed between the inlet side and the outlet side whose displacement with respect to a first position moderates a pressure drop between the inlet side and the outlet side, a diaphragm, an adjustable spring whose tension enables the diaphragm to displace the movable member with respect to the first position against a pressure imparted by a fluid in the outlet side, a communication port via which pressure is imparted on the diaphragm from the outlet side, a calibrated bypass that provides fluidic communication between the inlet side and the outlet side when the movable member is in the first position, and first and second outlets in fluidic communication with the outlet side. The second outlet is adapted and constructed to receive a pressure tank. The second outlet may include a union with a flat gasket.